According to the well known principles of fluid dynamics, as an aircraft flies through the air, a boundary layer of turbulent air develops about all exterior surfaces of the aircraft. In order to properly deploy an ordnance from underneath the aircraft, the ordnance must be pushed through this boundary layer before being fully released from control. If the ordnance is not pushed through the boundary layer, the turbulent air within the boundary layer may act unpredictably upon the ordnance, perhaps causing it to bounce against the under surface of the aircraft thereby causing damage.
Typically, ordnance ejector systems function either by mechanical linkages which push the ordnance through the turbulent boundary layer, or axially moving reciprocating shafts which push the ordnance through the turbulent boundary layer. Examples of the linkage type ordnance ejector systems include U.S. Pat. Nos. 4,440,365 to Holtrop, issued Apr. 3, 1984, 4,679,751 to Peterson, issued July 14, 1987 and 4,600,171 to Kalisz, issued July 15, 1986. An example of the axially moving reciprocating shaft type ordnance ejector system is the U.S. Pat. No. 4,572,053 to Sosnowski et al., issued Feb. 25, 1986.
Typically, the linkage type ordnance ejector systems include a forward and rearward linkage connected to a rail member, wherein the rail member releasably retains the ordnance thereto. It has been found particularly advantageous to individually control the forward and rearward linkage with separate, dedicated actuators. Such actuators typically comprise pyrotechnically operated pistons. Individual control of the forward and rearward linkages allows the ordnance ejector system to be more easily adapted to different ordnance types. That is, different types of ordnance may require different ejection velocities, different attitudes at release, etc. Unless independent control of the forward and rearward linkages is provided, such adaptations can not be made except by physical changes to the individual links.
One significant concern which becomes particularly acute when the forward and rearward linkages are controlled by independent actuators is the reaction forces placed upon the support frame structure when the two independent actuators are operated. According to the prior art, the support frame is designed from very strong and heavy members in order to withstand the reaction forces. However, the increased weight of the support frame has an adverse affect on the aircraft, as weight is always a critical factor in air travel.
Because of this, many prior art devices have foregone independent control of the forward and rearward linkages by separate actuators, favor of a single actuator so that the support frame does not need to be fabricated from heavy structural members.